Hi, right now I'm trying to teach someone about C programming. Specifically right now we're on pointers in C. However I feel this is a difficult concept to explain, as the person I'm teaching doesn't have much programming experience. I was wondering if anybody knew of a good tutorial on C pointers for a true beginner programmer?
I've tried searching on google however the results seem to assume the reader knows a lot.
Check these -
http://www.taranets.net/cgi/ts/1.37/ts.ws.pl?w=329;b=277
There is a book called "Pointers in C" by Yashwant Kanitkar which is really a good book to read and understand. Not sure if online version is available.
I wouldn't be teaching a beginner pointer arithmetic. It's probably better to start with a language that doesn't require that knowledge. Teaching someone C from the get go is like throwing them off a building and demanding they fly. I recommend starting with Scheme or maybe python. Once they get a grasp of data structures, and scope, and start wondering what's happening behind the scenes then I'd suggest C and pointers.
From my teaching experience, if you start with pointers without mixing them with dynamic memory allocation, they are pretty easy to grasp.
As already mentioned, pictures help a lot.
Once basic pointers are understood, you can move to arrays (still on stack) and pointers and they are related. Introduce pointer arithmetic (specifically the definition of the [] operator).
Once this is understood (very good test is let them implement palindrome testing using pointer arith), you can safely move to dynamic memory. Make sure you use valgrind heavily (not sure what is available on Windows).
You might want to take a look this book: The C Programming Language, by Brian Kernighan and Dennis Ritchie
If the student understands memory (bytes and words) and how variables reside within memory, it should be no problem for them to understand pointers (memory addresses).
Addendum
To clarify: the student needs to understand how variables are stored in memory in order to understand that pointers are variables whose values are memory addresses.
Think of pointer as an generalized idea of array index. And as index may point to array element, pointer may point to any variable in memory (imagine memory as great array!).
Accessing to array through index and variable (and array ofcourse) through pointer is much similar: index: array[i] pointer: *p
Compare two programs, one uses indexes, and another uses pointers
long x[20]; long x[20];
int i; long *p;
x[0] = 0; x[0] = 0;
x[1] = 1; x[1] = 1;
for(i = 2; i<20; i++) { for(p = x+2; p < x+20; p++) {
x[i] = m[i-1] + m[i-2]; *p = *(p-1) + *(p-2);
} }
That's the analogy. Hope this helps.
This is not really an answer, since I don't have a tutorial to point you to. I just want to follow up on the comment that said "draw lots of pictures" by saying: Yes! And find a good analogy you're comfortable with. Analogies aren't always cheesy and don't always begin with "it's kinda like a car..."
Here's one that helped me a lot: Try thinking about pointers as strings -- no, not text strings, but the real-world-piece-of-rope kind of string that you use to tie things with! The rôle of your data is played by any real-world object in a really peasoup-foggy place. Maybe you can't even see the data from where you're standing.
Thus:
This silly analogy helped me a lot. I know it doesn't cover pointer arithmetic, but I think that's easier to grasp if you feel at home with pointers in the first place.
pointer are "address" like postal address. When you want to store something in the pc, it's like on earth, you must create a "storage house". This is called memory allocation. Once the storage house is built, you can store and get back thing into it. To do it you use the address of the storage house, that's the pointer. To access the content of the pointer, you write *pointer, etc... Hope you understand the idea :)